Most people today celebrate vaccination as a great achievement, yet many nineteenth-century Americans opposed it, so much in fact that states had to make vaccination compulsory. In response, antivaccination societies formed all over the United States, lobbying state legislatures and bringing lawsuits to abolish these laws. One such lawsuit ultimately arrived at the United States Supreme Court, which upheld the laws in a landmark decision, Jacobson v. Massachusetts (1905). In this study, Karen Walloch examines the history of vaccine development in the United States, the laws put in place enjoining the practice, and the popular reaction against them. Walloch finds that at the end of the nineteenth century Americans had good reason to fear vaccination. Vaccines simply did not live upto claims made for their safety and effectiveness. They induced pain, disability, and grim or even fatal infections. In this critical history of the antivaccine movement and of Jacobson v. Massachusetts in particular, Walloch locates the beginnings of a legacy of doubt about vaccination -- one that affected legislation in all fifty states and is still very much alive today. Karen Walloch is a historian who teaches at the University of Wisconsin-Madison.